Objectives of the Cooperative Breast Cancer Group are the design and execution of cooperative studies to evaluate the course and therapy of specific malignant disease processes on a prospective controlled basis. Such studies may include evaluation of etiology, natural history, prognosis, pathology, immunology and other pertinent aspects as correlaries to main emphasis on therapy. Our institution proposes to participate in studies utilizing hormonal and chemotherapeutic agents, alone and in combination, to assess their efficacy in breast cancer and other malignant diseases as protocols are evolved. A large patient population is available for these studies. Definition of parameters of patient selection for most appropriate modalities of therapy utilizing new techniques for such assessment remains the major goal of this study group.